КООРДИНАЦИОННАЯ ХИМИЯ, 2013, том 39, № 8, с. 487-491
УДК 541.49
SYNTHESIS, CHARACTERIZATION, AND X-RAY CRYSTAL STRUCTURES OF COPPER(II) AND NICKEL(II) COMPLEXES WITH SCHIFF BASES
© 2013 H. Y. Liu
School of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, Zhongshan, 528453 P.R. China
E-mail: liuhuanyu03@163.com Received November 14, 2011
New copper(II) complexes, [Cu2L1L2] • ClO4 (I) and [Ni(L3)2] (II), where L1 is the mono-anionic form of 2-[1-(2-emthylaminoethylimino)ethyl]phenol, L2 is the dianionic form of N,N'-ethylene-¿is(2-hydroxy-acetophenonylideneimine), L3 is the mono-anionic form of 2-(1-iminoethyl)phenol, were prepared and characterized using elemental analysis, FT-IR spectroscopy, and X-ray single-crystal diffraction. In complex I, the Cu(1) atom is coordinated by the NNO tridentate ligand L1 and the two phenolate O atoms of L2, forming a square pyramidal geometry. The Cu(2) atom in complex I is coordinated by the NNOO tetradenate ligand L2, forming a square planar geometry. The Ni atom in complex II is coordinated by two phenolate O and two imine N atoms from two ligands L3, forming a square planar geometry. In the crystal structure of I, the per-chlorate anions are linked to the dinuclear copper(II) complex cations through intermolecular N—H---O hydrogen bonds. In the crystal structure of II, the mononuclear nickel complex molecules are linked through intermolecular N—H---O hydrogen bonds, forming a trimer.
DOI: 10.7868/S0132344X13070062
INTRODUCTION
Schiff bases are a kind of versatile ligands in coordination chemistry. The compounds containing strong donor sites, such as phenoxo oxygen and imine nitrogen atoms have attracted much attention in catalysis and biological application for their special coordination ability with transition metal atoms [1—4]. In particular, copper and nickel complexes with Schiff base ligands have received considerable interest in the fields of medicinal chemistry for their antibacterial, antitumor and antifungal activities [5—8]. Recently, we have reported a few Schiff base complexes [9]. As an extension of the work on such complexes, in this paper, a new dinuclear copper(II) complex [Cu2L1L2] • ClO4 (I) and a new mononuclear nickel(II) complex [Ni(L3)2] (II), where L1 is the mono-anionic form of 2-[1-(2-emth-ylaminoethylimino)ethyl]phenol, L2 is the dianionic form of N,N'-ethylene-W,s(2-hydroxyacetophe-nonylideneimine), L3 is the mono-aninic form of 2-(1-iminoethyl)phenol, were prepared and structurally characterized.
EXPERIMENTAL
Materials and physical measurements. 2-Acetylphe-nol, ethane-1,2-diamine, and N-methylethane-1,2-diamine were purchased from Lancaster Chemical Company Inc. Copper perchlorate was prepared by the reaction of Cu2(OH)2CO3 with perchloric acid in distilled water. Nickel acetate was purchased from Sin-
peuo Fine Chemical Company Inc. and used as received. All other chemicals were ofAR grade. Elemental analyses for C, H, and N were performed using a PerkinElmer 240C elemental analyzer. Infrared spectra were recorded on a Nicolet 170SX FT-IR spectrophotometer with KBr pellets in the 4000—400 cm-1 region. Molar conductance measurements were performed in a DDS-11A conductivity meter.
Synthesis of complex I. 2-Acetylphenol (0.136 g, 1 mmol), N-methylethane-1,2-diamine (0.037 g, 0.5 mmol), and ethane-1,2-diamine (0.030 g, 0.5 mmol) were mixed in methanol (20 mL). The mixture was stirred at ambient temperature for 30 min. To the above mixture was added dropwise a methanolic solution (10 mL) of copper perchlorate (0.388 mg, 1 mmol) with stirring. The final mixture was further stirred at ambient temperature for 30 min to give a blue solution. The blue single crystals of I suitable for X-ray analysis were obtained several days later. The yield was 51%.
For C29H33N4O7ClCu2
anal. calcd., %: Found, %:
C, 48.91; C, 48.73;
H, 4.67; H, 4.75;
N, 7.87. N, 7.96.
Selected IR data (KBr; v, cm-1): 3344 w, sh; 1604 s, 1553 m, 1474 m, 1439 s, 1305 s, 1236 s, 1106-1066 v.s, 858 m, 769 m, 624 w, 588 w, 523 w, 439 w.
Synthesis of complex II. 2-Acetylphenol (0.136 g, 1 mmol) and a few drops of ammonia water were mixed in methanol (20 mL). The mixture was stirred at
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Table 1. Crystallographic data and details of refinements for complexes I and II
Parameter Value
I II
Formula weight 712.1 327.0
Crystal system Triclinic Triclinic
Space group PI PI
Unit cell dimensions:
a, A 10.434(1) 9.096(2)
b, A 11.355(1) 11.351(2)
c, A 13.079(1) 11.790(2)
a, deg 101.306(2) 100.947(2)
ß, deg 97.326(2) 93.050(2)
Y, deg 97.885(2) 109.682(2)
V, A3 1486.0(1) 1116.3(3)
Z 2 3
Pcalcd g cm-3 1.591 1.459
/(000) 732 510
p.(MoÄ"a, mm-1 1.574 1.308
9 Range, deg 1.6-27.0 2.3-27.0
Index ranges h, k, l -13 < h < 13, -14 < k < 9, - 16 < l < 16 -11 < h < 11, -14 < k < 14, -15 < l < 14
Collected reflections 8538 9245
Independent reflections (Rint) 6150 (0.0246) 4768 (0.0268)
Observed reflections (I > 2a(I)) 3856 3545
Parameter 395 298
Ri (I > 2a(I)) 0.0473 0.0388
wR2 (I> 2a(I)) 0.1089 0.0845
Goodness-of-fit on F 2 1.011 1.029
Largest diff. peak and hole, e A-3 0.766 and -0.631 0.488 and -0.306
ambient temperature for 30 min. To the above mixture was added dropwise a methanolic solution (10 mL) of nickel nitrate (0.291 g, 1 mmol) with stirring. The final mixture was further stirred at ambient temperature for 30 min to give a red solution. The red single crystals of II suitable for X-ray analysis were obtained several days later. The yield was 36%.
For Ci6Hi6N2O2Ni
anal. calcd., %: C, 58.77; H, 4.93; N, 8.57. Found, %: C, 58.95; H, 5.01; N, 8.46.
Selected IR data (KBr; v, cm-1): 3320 m, sh; 1604 s, 1534 m, 1472 w, 1437 s, 1406 w, 1335 s, 1276 s, 1254 w,
1219 m, 1155 w, 1133 m, 1033 w, 989 w, 874 m, 847 w, 830 w, 771 w, 746 m, 591 w, 508 w, 457 m.
X-ray structure determination. The crystal and instrumental parameters used in the unit cell determination and data collection are summarized in Table 1. Diffraction measurements were made 298(2) K on a Bruker SMART APEX II X-ray diffractometer using graphite-monochromated MoZ„ radiation using ® scan mode. Unit-cell dimensions were determined and refined in the 2.61° < 9 < 27.00° range for I and in the 2.33° <9 < 27.00° range for II. The program SMART [10] was used for data collection, indexing reflection and determination of lattice parameters, SAINT [10] for integration of the reflection intensity and scaling and SADABS [11] for absorption correc-
SYNTHESIS, CHARACTERIZATION, AND X-RAY CRYSTAL STRUCTURES OF COPPER(II)
489
tion. The structures were solved by the direct method using SHELXS-97 and refined by full-matrix least-squares techniques on F2 with SHELXL-97 [12, 13]. All non-hydrogen atoms were refined with anisotropic displacement parameters. The amino hydrogen atoms in both complexes were located from difference Fourier maps and refined isotropically with N—H distances restrained to 0.90(1) A and with ^iso(H) values set to 0.08 A2. The remaining hydrogen atoms were included in their idealized positions and refined isotropically. Selected bond distances and angles for complexes are list in Table 2. Hydrogen bonding geometries are given in Table 3. Supplementary material for structures I and II has been deposited with the Cambridge Crystallo-graphic Data Centre (nos. 853812 (I) and 853813 (II); deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac. uk).
RESULTS AND DISCUSSION
The copper complex was prepared by reaction of 2-acetylphenol, N-methylethane-1,2-diamine, ethane-1,2-diamine, and copper perchlorate in methanol at ambient condition. The nickel complex was prepared by reaction of 2-acetylphenol, ammonia water, and nickel nitrate in methanol at ambient condition. The structures of the complexes were characterized by elemental analysis, IR spectra, and single crystal X-ray diffraction. The molar conductivity measurements of the complexes in DMSO at the concentration of 10-3 mol/L suggest that the copper complex is a 1 : 1 electrolyte, and the nickel complex is a non-electrolyte, with the conductance values of 173.5 fi-1 cm2 mol-1 for I and 19.0 fi-1 cm2 mol-1 for II, respectively [14].
The molecular structure of the dinuclear complex I is shown in Fig. 1a. The Cu—Cu separation is 3.166(1) A. The Cu(1) atom is in a distorted square pyramidal coordination, with the NNO donor atoms of L1 and one phenolate O atom of L2, defining the basal plane, and with the other phenolate O atom of L2 occupying the apical position. The distortion of the square pyramidal coordination can be observed from the bond angles between the apical and basal donor atoms, ranging from 70.6(1)° to 113.6(1)°. The Cu(2) atom is in a square planar coordination, with two phenolate O and two imine N atoms of L2. The bond lengths related to the Cu atoms are comparable with those observed in other Schiff base copper complexes with similar coordination [15, 16]. In the crystal structure of the complex, the perchlorate anions are linked to the dinuclear complex cations through intermolecular N-H---O hydrogen bonds, as shown in Fig. 2a.
The molecular structure of the mononuclear complex II is shown in Fig. 1b. The asymmetric unit of complex II contains three independent molecules linked together by four intermolecular N-H---O hydrogen bonds (Fig. 2b). The Ni atom is coordinated by two phenolate O and two imine N atoms from two L3, forming a square planar coordination. The adjacent
Table 2. Selected bond lengths (A) and angles (deg) for complexes I and II
Bond d, A Bond d, A
Cu(1)-O(1) Cu(1)—O(3) Cu(1)—N(2) Cu(2)—O(3) Cu(2)-N(4) Ni(1)-O(3) Ni(2)-O(1) Ni(2)-N(1) 1.868(3) 2.061(3) 1.997(4) 1.900(3) 1.928(4) I 1.816(2) 1.822(2) 1.846(2) Cu(1)-O(2) Cu(1)-N(1) Cu(2)-O(2) Cu(2)-N(3) I Ni(1)-N(3) Ni(2)-O(2) Ni(2)-N(2) 2.293(3) 1.963(3) 1.882(3) 1.921(4) 1.849(2) 1.823(2) 1.843(2)
Angle ro, deg Angle ro, deg
I
O(1)Cu(1)N(1) 93.0(1) O(1)Cu(1)N(2) 172.4(2)
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